What hold galaxies together?

Of course gravity is an acceleration. Down here on Earth it has a value of 9.8 metres per second per second or 32 feet per second per second.

 

That is a basic physics concept. Also, you are again resorting to personal attacks instead of intelligent discourse.

 

What hold galaxies together?
It looks like tonight it's Argo's


Actually I think that galaxies are not being held together at all.
That would imply they are static.

“The flow of energy through a system acts to organize that system.”
Haroid Morowitz

 

When you step off a ledge and hit the ground you will discover to what degree the alleged force is "pseudo".

 

not quite
Some confusion here

The force of gravity on earth causes a mass to accelerate at 32 ft per sec per sec

Gravity itself is not an acceleration

Force of gravity = G ( a constant)x m1 x m2 / r2 This is Newtons law. This equation calculates the force acting due to gravity between two masses

 

The law of gravitation (Newton/Einstein, choose your flavor) applies at any scale where the mass concept makes sense, and outside the influence of greater interactions. So let's simply consider the moon orbiting the earth. If the law of gravitation applies here, then we can all make the same observation : The moon has a movement around the earth, and is not static, in that the moon do not stay at the same place, in relation with the earth. But isn't the moon held in her orbit by the mass of the earth ? Do holding something imply that all his degree of freedom should be zero ? Isn't that fixity instead ?

The moon is not fixed. His trajectory is a stationnary orbit. A collection of bodies held into stationnary trajectories is indeed organized following the principle of less energy. This is what is used when you solved mechanical systems of equations expressed into Lagrange or Hamilton form. Trivial solutions of such systems are constant in time, while stationnary solutions are not.

 

You are completely misunderstanding what a pseudo-force is. Go back to Wikipedia.

 

That works if the frame of reference has 0,0,0 at the center of the Earth. From the Sun as frame of reference, ignoring translation, they both rotate around a point at a distance proportional to the mass of each body.

 

I think you will find that the in any language or science, the fact that galaxies exist as clumps separated by thousands of galactic diameters from their nearest neighbours, and appear to have done so for billions of years qualifies for "being held together".

 

When performing transformations between frames of reference we have to remember to use inertial frames of reference, i.e ones which do not rotate or accelerate. As soon as you start considering systems involving gravity, you have to remember that gravity is an acceleration and so it is invalid to perform transformations between, for example, one with the earth at the centre and one with the sun.

 

I am afraid you are creating the confusion. Gravity is not a force, it is an acceleration: check its dimensions LT-2.
The force required to prevent an object of mass "m" accelerating in a gravitational field of strength "g" is m x g. The component "g" is an acceleration.

 

Not at all as long as it is stated. As I described, a person at the center of the earth sees the moon rotating around it. A person at the sun, sees the earth and the moon rotating about a point proportional to their masses. It is something that started when the Geocentric theory was proven wrong.

 

@gonzo Actually a person at the centre of the earth doesn't see the moon at all!
A person on the surface of the earth sees the moon rise and set. It's the astronomers who deduced, from their observations, that the moon orbits the earth and the earth orbits the sun. Some time later they discovered that the orbits were influenced by the respected mass and their distance from each other. They didn't do any transformations into different frames of reference to do that.
From any and all frames of reference, the moon orbits the earth and the earth orbits the sun (or more precisely the moon and the earth orbit a centre of mass and the earth and sun orbit a different centre of mass. )

 

Actually it is entirely possible to transform between frames of reference with the systems rotating and accelerating relative to each other. The math used is more complicated though.

 

I think that is one of the best Free Floating Rational I have ever read.
Thanks for setting me straight.